Computer Controled Timing. Help me build ignition timing map

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luftvagon
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Location: Little Rock, AR
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Computer Controled Timing. Help me build ignition timing map

Post by luftvagon » Mon Jun 10, 2013 12:32 pm

Load (manifold absolute pressure) based Computer Controlled Ignition timing map

I need your help in designing a load based ignition timing map. I will be working off these charts to build a a base map, and tune it for performance at max load, and economy at cruising load. In addition, the system will sport a knock sensor to help-out when it needs to. :salute:

Image Image
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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SlowLane
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Re: Computer Controled Timing. Help me build ignition timing

Post by SlowLane » Mon Jun 10, 2013 10:00 pm

Why don't you just start with the advance curves given in the Old Volks Home distributor specification list?

For the '80 - '83 Federal Vanagon, that's:
Advance/Retard Range: Vacuum: 8-12deg Adv @ 7.9 In. Hg; Centrifugal: 9-14deg @ 1600 rpm, 21-25deg @ 3400 rpm
'81 Canadian Westfalia (2.0L, manual), now Californiated

"Wisdom comes from experience. Experience is often a result of lack of wisdom."
- Terry Pratchett

luftvagon
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Location: Little Rock, AR
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Re: Computer Controled Timing. Help me build ignition timing

Post by luftvagon » Tue Jun 11, 2013 5:41 am

I am. That will be my base map. :bounce:
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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SlowLane
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Re: Computer Controled Timing. Help me build ignition timing

Post by SlowLane » Tue Jun 11, 2013 8:57 am

Okay, then what sort of help are you asking for, exactly? :scratch:
'81 Canadian Westfalia (2.0L, manual), now Californiated

"Wisdom comes from experience. Experience is often a result of lack of wisdom."
- Terry Pratchett

luftvagon
Old School!
Location: Little Rock, AR
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Re: Computer Controled Timing. Help me build ignition timing

Post by luftvagon » Tue Jun 11, 2013 10:44 am

I'll need your opinion on what it should look like at light/medium load cruise... how much advance it should have... i feel that with distributor you don't get to take advantage of what this motor could do.
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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Amskeptic
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Re: Computer Controled Timing. Help me build ignition timing

Post by Amskeptic » Wed Jun 19, 2013 9:56 pm

luftvagon wrote:I'll need your opinion on what it should look like at light/medium load cruise... how much advance it should have... i feel that with distributor you don't get to take advantage of what this motor could do.
"What this 'motor' could do" at light/medium load cruise is just what any engine does at light/medium cruise. Note that the 205P has the best curve for stock output, lots of advance in the vacuum signal under light loads and it ramps up then stops the centrifugal advance seriously around the 3,000 rpm range while that svda is lagging.

Tuning for maximum load is the province of the centrifugal advance since your vacuum signal will be out.
Tuning for maximum economy will be the province of the vacuum advance, off-throttle overrun stock is at 38-40* total advance, dropping back as the vacuum drops.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 94,615 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,990 miles

luftvagon
Old School!
Location: Little Rock, AR
Status: Offline

Re: Computer Controled Timing. Help me build ignition timing

Post by luftvagon » Mon Sep 02, 2013 4:18 pm

Here is my current running ignition map:

Image

Current engine layout (mind the lack of distributor):

Image

Let me know how you'd like to see the ignition map. I can load it and test it, and document it.
I idle at 40 kpa. Stady state light load cruise is at 80kpa. =) Everything past 85kpa is load.
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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Amskeptic
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Re: Computer Controled Timing. Help me build ignition timing

Post by Amskeptic » Sat Sep 07, 2013 7:42 pm

luftvagon wrote:Here is my current running ignition map:
Please label the Y axis.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 94,615 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,990 miles

luftvagon
Old School!
Location: Little Rock, AR
Status: Offline

Re: Computer Controled Timing. Help me build ignition timing

Post by luftvagon » Sun Sep 08, 2013 5:14 pm

Image

AFR to match:

Image
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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